This invention is directed to a locking mechanism which requires both a key and a corresponding combination wheel position to open the locking mechanism. A recorder records the combination wheel setting each time the lock is opened.
One of the types of mechanisms which has been developed to limit access to a designated space is the combination lock. In this case, one or more lock members must be set into an unlocking position by manipulation of one or more manual input elements. The numbered dial is often used, and either one dial is sequentially turned to successive positions or a plurality of dials is each set to a particular position to cause unlocking. The advantage of a combination lock is that a key may be lost or stolen, but a memorized combination is secure until disclosed by the person having the combination.
Another common type of lock is the key lock wherein a specially shaped key is inserted into the lock. The key causes mechanical action in the lock to position tumblers so that the lock is unlocked. Key locks may have a very complicated key-tumbler structure to increase the difficulty of lock-picking. However, loss of the key to another person permits access to the lock-protected space by that person. Furthermore, such keys can and sometimes must be duplicated so that many persons have access, with a greater chance of loss of control. Additionally, when many persons have keys and thus access to protected space, it is not known which of those among the authorized key holders have had access to that space. In order to identify the key user, U.S. Pat. No. 1,253,051 provides a key which has a first set of notches for properly positioning locking tumblers into the unlocked position and has a second set of notches which are peculiar to that key for actuating a recording device for recording which key has been used to open the lock and thus, presumably, identify the key user. However, such a key can be lost, duplicated, or the identifying portion can be altered or defaced to reduce the security of its recording system.
Another type of lock is the key-controlled combination lock. An example of this type of lock is shown in U.S. Pat. No. 3,383,886. In this type of lock, a key is used to unlock the combination dial, and once unlocked, the combination dial then is actuated to unlock the secured space. This type of lock provides the security of having possession of a key and possession of a combination to provide access to the secured space. Thus, loss or duplication of the key does not compromise the space because both knowledge of the combination and possession of the key are necessary for access. When a plurality of persons is permitted access, then the chances of compromise are compounded because the combination can be obtained from one holder and a key from another or by duplication. Furthermore, such a locking structure cannot provide for identification of the user so that, if compromised, that person cannot be identified.
Therefore, there is need of a locking mechanism which can be arranged so that it may be opened by a large number of people, but recording of the user can be achieved. Furthermore, it is desirable to maximize security of such a system by providing a structure wherein each user has two sets of unique information which cooperate together in the locking mechanism to permit access to the secured space and, at the same time, record information related to the user.